There are three main types of dental impressions — preliminary, final, and bite registration.
The preferred elastomeric impression materials on the market are polyvinyl siloxanes (PVS) and polyethers (PE). Polyethers are known for their hydrophilic properties and good flowability. Polyvinyl siloxanes , on the other hand, are known for their excellent elasticity, high tear strength and stability.
This article will discuss the 3 most common classifications of impression materials : polyether (PE), vinyl polysiloxane (VPS), and a hybrid material called vinyl polyether siloxane (VPES).
1. What type of impression material will be used for this impression ? The alginate impression material will be used for this preliminary impression .
A good impression should have clear facial surface of the teeth /margins, no voids, no pulls or see through of tray. This opens in a new window. Select the best fitting tray, this can help to ensure clear margins. Try the tray in the mouth before taking the impression .
Dental impressions are made one of two ways. Traditional impressions use trays with an FDA approved jelly material. In order for the impression to set, it must remain in a patient’s mouth for two to three minutes. Once completed , the material hardens and creates a mold of the teeth .
CHAIRSIDE® Heavy Body Impression Material is an additional-cure vinyl polysiloxane (VPS) material developed to capture accurate impressions in a predictable and consistent manner.
Polyvinyl siloxane ( PVS ), also called poly-vinyl siloxane, vinyl polysiloxane (VPS), or vinylpolysiloxane, is an addition-reaction silicone elastomer (an addition silicone). Polyvinyl siloxane is widely used in dentistry as an impression material .
Impression trays are supplied as quadrant trays , which cover half of the arch; section trays , which are suited for the anterior teeth; and full arch trays , which cover the complete arch.
Impression materials Plaster of Paris (impression plaster ) Impression compound. Vinyl polysiloxane impression material (impression material) Zinc-oxide eugenol plaster (impression paste) Hydrocolloid . Polysulphides. Polyethers. Silicones.
Conclusions: Most addition silicone materials provide higher tear strengths than polyether and hybrid materials. Materials display higher tear strengths after longer set times and at faster tearing rates. Impressions should be removed from the mouth with the fastest possible speed.
elastomeric materials use an Automix system. the extruder gun insert is a dual cartridge with a tube of catalyst and a tube of base. although technique may vary, when assisting a dentist in taking an elastomeric impression , mix the light-bodied material first.
Elastic impression materials can be further divided into hydrocolloid and elastomeric impression. Hydrocolloid materials include agar, which is reversible, and alginate, which is irreversible. Elastomeric materials include polysulfide, polyether, condensation-cured silicone, and addition-cured silicone.
The lower impression is typically done first , followed by the upper. Because the impression has to get to the back of your mouth to get the back teeth, some patients think the alginate is going to slide down their throat. Don’t worry – it won’t. Orthodontic assistants take many impressions every day.